Chemometric study for the performances of deep eutectic solvents during the recovery of high-added-value substances from Moringa oleifera leaves: Principal component analysis.

INTRODUCTION: Moringa oleifera is a plant with high antioxidant content in its leaves, flowers and seeds. It attracts the attention of researchers with the effect of its nutritional and medical advantages. OBJECTIVE: The purpose of the current study is to propose a deep eutectic solvent (DES)-based ultrasound-assisted extraction of bioactive substances from M. oleifera leaves by the application of a chemometric study. METHODOLOGY: A total of 18 different choline chloride-based DESs were prepared by using several hydrogen bond donors (glucose, sucrose, glycerol, ethylene glycol, urea and dimethyl urea) with various molar ratios (1:1, 1:2 and 2:1) by addition of diluents (water and 50% methanol) or alone. In order to decide the best DES combination, principal component analysis (PCA) was applied. The response surface method (RSM) was used as statistical experimental design approach through the Box-Behnken design. RESULTS: The best phenolic (TPC), flavonoid (TFC) and antioxidant activity yields of M. oleifera leaf extract were found to be 19.102 mg-GAE, 10.47 mg-CE and 24.404 mg-TEAC per gram dried leaf under the optimal conditions (50% water content, 20% amplitude, 15 min time). The model fitting has been also found reliable depending on the statistical indicators such as p-value (<0.0001), coefficients of determination (R2 = 0.9827, 0.9916 and 0.9864) and root mean square error (RMSE = 1.0562, 2.4656 and 0.7713). CONCLUSIONS: A chemometric study through PCA was carried out to determine the similarities and differences between the solvent groups, and the ethylene glycol-based DES (1:2, molar ratio) with the addition of water showed the best performance.

Investigation of Bioactivity Degradation During Storage of Sour Cherry (Prunus cerasus L.) Peel Extract.

INTRODUCTION: Limited number of researches in the literature have been reported to examine degradation stability by regression methods. Monitoring storage stability of plant extracts containing phytochemicals has become a special field. OBJECTIVE: This study aims to develop model equations to examine the stability of total phenolic material (TPM) and total anthocyanin (TA) in the sour cherry peel extract under several conditions, such as keeping the samples in a freezer (-20°C), refrigerator (4°C) and room temperature (25°C) conditions. In addition, two types of ambient conditions (under dark and light, respectively) were applied to observe the effect of sunlight on oxidation. METHODS: The storage stability was monitored in terms of TPM and TA. 8 different polynomial regression equations were produced for the data obtained under each condition in order to define the deterioration of the TPM and TA during 60 days of the storage. RESULTS: Keeping the samples in the light at ambient conditions was the least efficient for stability (~10 days), while the shelf life of the product could have been quite long with the storage in the freezer after opening the package of the product. CONCLUSIONS: The most suitable condition for both TPM and TA has been determined as -20°C with the calculation of degradation days as 157 and 115 (R^2 = 0.9874 / 0.9265, and average error rates = 0.207097% / 0.119541%).

Adsorption of rutin from olive mill wastewater using copolymeric hydrogels based on N-vinylimidazole: Kinetic, equilibrium, and thermodynamics assessments.

Olive mill wastewater, also known as olive wastewater, contains biologically active components with various beneficial effects on health. The development of novel adsorbent materials for the recovery of these biologically active substances is important area of research. In this study, copolymeric hydrogels based on N-vinylimidazole (VIm), a new material that has never been used as an adsorbent in the separation of phenolic components, were synthesized. The hydrogels synthesized in this study is copolymer structures based on N-vinylimidazole (VIm) containing [2- (methacryloxy) ethyl] dimethylpentylammonium bromide (QDMAC5) in different moles. QDMAC5 was obtained by quaternization of 2- (dimethylamino) ethyl methacrylate (DMA) with 1-bromopentane (C5). The production of copolymer hydrogels was carried out by free radical solution polymerization. The syntheses were carried out only by changing the monomer composition so that the crosslinker ratio remained constant (1.2 mol%). The QDMAC5 content in the copolymers was 5, 10, 20, 30, and 50 mol%. So, the resulting structures were named PVQ-5%, PVQ-10%, PVQ-20%, PVQ-30%, and PVQ-50%, respectively. Functional group characterizations of hydrogels were made by Fourier Transform Infrared Spectrometry (FTIR). The surface of the hydrogels was analyzed by Scanning Electron Microscopy (SEM). Finally, thermogravimetric analyzes (TGA) were performed to investigate the thermal degradation behavior. The recovery of the rutin present in olive mill wastewater has been investigated as a model study. Kinetic data has been represented by the selected models (pseudo-first order, pseudo-second order, and intraparticle diffusion) convincingly (R2 > 0.76), while the equilibrium findings have fitted well to Langmuir, Freundlich, and Temkin equations (R2 > 0.77). Rutin adsorption process on N-vinylimidazole (VIm) based copolymeric hydrogels has been found as exothermic and spontaneous chemisorption process depending on the thermodynamic analysis.

Special designed deep eutectic solvents for the recovery of high added-value products from olive leaf: a sustainable environment for bioactive materials.

Deep Eutectic Solvents have been specially designed, and used for the extraction of phenolics from olive tree (Olea europea) leaves. 11 deep eutectic solvents containing a hydrogen bond donor (glycerol, ethylene glycol, lactic acid, urea, dimethyl urea and D-sorbitol) and a hydrogen bond acceptor (L-proline, citric acid, glycerol, ethylimidazole and methylimidazole) with several molar ratios have been designed. Addition of water into the solvent system increased the extraction efficiency by a remarkable difference (45%). After the best combination has been decided to extract the primary phenolic (oleuropein), operation conditions (water content in the deep eutectic solvent, speed of the homogenizer and time for the extraction) of the homogenizer-aided extraction (HAEX) for olive leaf extract has been optimized through Box-Behnken design of Response Surface Approach. The experimental yields of oleuropein, verbascoside and rutin were 15.50, 5.51 and 0.98 mg per gram dried leaf under the optimal conditions (48.9% of water in DES for 60 sec at 13310 rpm). Our best DES (citric acid/lactic acid) has yielded the most efficient extract rich in oleuropein, even with an ≈8% higher performance than that of a most commonly used solvent (75% ethanol).

Improving the quality of vegetable oils treated with phytochemicals: a comparative study.

In this study, sunflower, corn, peanut and hazelnut oils were investigated according to their oxidative stability and antioxidant activity parameters. The related vegetable oils were treated with gallic acid, rutin and carotenoid. Olive leaf extract having a large variety of phytochemical was also valorized. After the leaf samples were extracted through a homogenizer, they were added into the vegetable oils, respectively. Moreover, synthetic antioxidants were also dissolved into the oils for control reasons. Stability of the vegetable oils against the oxidation was evaluated via Rancimat by measuring induction time. The quality parameters of treated and untreated oil samples were compared depending on phenolic and carotenoid contents, antioxidant activity and induction time.

Kinetics and thermodynamics evaluation of oxidative stability in Oleum hyperici: A comparative study.

In this study, Oleum hyperici (St. John's Wort oil) was investigated according to its oxidative stability and antioxidant activity parameters. A homemade and two different brands of oils were used for comparative reasons. Oxidation process regarding kinetics and thermodynamics studies achieved by accelerated Rancimat conditions (100-140 °C). The quality parameters of the oil samples were compared depending on phenolic and flavonoid contents, antioxidant activity, free fatty acid quantity and shelf-life. Principal component analysis (PCA) has been also applied to comprehend the relationship between these three groups and their quality parameters. The homemade oil has been predicted to have almost twice longer shelf-life than that of the commercial ones (119 days versus 66/69 days). Additionally, lipid oxidation in the St. John's Wort oils has been found to be endothermic and non-spontaneous depending on the thermodynamic indexes.